(a) Field of the Invention
The present invention relates to an apparatus for currency validation, in particular to improvement of a device for preventing unauthorized removal of a bill received in the apparatus.
(b) Description of the Prior Art
Current bill handling apparatuses include money exchanging or vending machines each provided with a bill validator for identifying the authenticity or denomination of a bill or paper currency inserted therein. When inserted into an inlet of the validator, the bill is conveyed by a belt-pulley arrangement to a sensor which detects optical or magnetic characteristics of the bill. When the bill validator identifies the insertion with a genuine bill from outputs of the sensor, it is then carried to a stacker wherein bills are accumulated for storage while exchanged bills or coins or goods are put out in a tray of the machine. Adversely, if the bill validator can not decide the insertion as a genuine bill, the belt-pulley arrangement is driven in the reverse direction to return same to the inlet. For instance, U.S. Pat. No. 4,628,194 indicates a prior art validator and U.S. Pat. No. 4,722,519 shows a stacker apparatus.
In some cases, a string-like material such as a thread or tape is intentionally attached to one end of a bill which is then inserted into the inlet of the validator. The bill is transported along a passageway in the bill validator by the belt-pulley arrangement through the sensor to the stacker or an escrow compartment as shown in U.S. Pat. No. 4,050,562, and an exchange is thrown out on the tray of the apparatus. After that, the bill is pulled back from the apparatus by pulling the string.
Many attempts have been made in the past for preventing unauthorized removal of a bill contained within the stacker. FIGS. 6 and 7 show a prior art apparatus for preventing improper removal of a bill. As illustrated, a passageway 1 is provided in a bill validator for transporting a bill 7 to a stacker or escrow compartment. Firstly, entry of the bill 7 into an inlet of the passageway 1 is detected by an optical sensor (not shown) which produces an electric signal to a control unit. Upon occurrence of the signal from the optical sensor, a feed motor is activated to carry the bill 7 toward the stacker by means of a belt-pulley arrangement. On the way of movement of the bill, a sensor detects optical or magnetic characteristics to convert same into electric signals to the control unit.
A lever 2 is mounted on a shaft 3 for rotation between a protective position protruded within the passageway 1 and a release position retracted from the passageway 1. A spring 4 is wound around the shaft 3 to resiliently urge the lever 2 toward the protective position.
When the bill 7 passes through the lever 2, a leading edge of the bill 7 comes into contact with and forcibly turns the lever 2 in clockwise direction against weak resilient force of the spring 4. Accordingly, the lever 2 is rotated by the bill 7 to the release position retracted from the passageway 1. After the bill 7 has passed over the lever 2, elastic force of the spring 4 returns the lever 2 to the protective position protruded within the passageway 1.
Once the bill 7 has passed beyond the lever 2, it prevents withdrawal of the bill 7 toward the inlet as the lever 2 protrudes within the passageway 1 under the resilient force of spring 4, and the lever 2 frustrates an attempt to pull back the bill 7.
However, it is possible to insert a thin tool 8 into the passageway 1 as illustrated in FIG. 7 and to push down the lever 2 to the release position by the tool 8 against the weak force of spring 4. In this case, by pulling the string material 6, the bill 7 may be pulled back beyond the lever 2 which is kept in the release position by the tool 8.